Selective call receivers (radio pagers) having voice message delivery capability are well known in the art. A disadvantage inherent in real-time voice radio communications, such as radio voice paging, is that in areas somewhat removed from a transmission source, i.e., "fringe" areas, as well as in close-in areas where there is shadowing from tall buildings, reception is compromised by multipath signal fading. In the case of a receiver traveling in a vehicle (a common environment for a radio pager), multipath fading typically is characterized by brief, e.g., less than one millisecond, deep signal fades. Such deep fades are typically flanked by longer, e.g., one-hundred millisecond, periods of relatively good signal strength. When a voice message is listened to in this fading signal environment, brief noise bursts are perceived in the received audio, which are annoying and can reduce perceived quality as well as intelligibility of the voice message.
Recent advances in digital technology have made it economically feasible to add voice storage capability to radio paging receivers. Voice storage has allowed a voice message to be digitized and stored in a digital memory of the selective call receiver for immediate recall and playback by a user desiring to hear the voice message again. Unfortunately, conventional radio paging receivers--even those with the new voice storage feature--have continued to suffer from the audio noise bursts caused by a fading radio signal environment.
Thus, what is needed is a method and apparatus for improving the perceived quality of voice messages received in a fading radio signal environment. Such an improvement in perceived quality would be particularly desirable in pagers with voice storage capability, which necessarily are more costly to manufacture and are therefore likely to invoke higher performance expectations from users.